This invention generally relates to intravascular catheters, such as balloon catheters used in percutaneous transluminal coronary angioplasty (PTCA), stent delivery, and drug delivery.
PTCA is a widely used procedure for the treatment of coronary heart disease. In this procedure, a balloon catheter is advanced into the patient""s coronary artery and the balloon on the catheter is inflated within the stenotic region of the patient""s artery to open up the arterial passageway and thereby increase the blood flow there through. To facilitate the advancement of the catheter into the patient""s coronary artery, a guiding catheter having a preshaped distal tip is first percutaneously introduced into the cardiovascular system of a patient by the Seldinger technique through the brachial or femoral arteries. The guiding catheter is advanced until the preshaped distal tip of the guiding catheter is disposed within the ascending aorta adjacent the ostium of the desired coronary artery, and the distal tip of the guiding catheter is then maneuvered into the ostium. A balloon catheter may then be advanced through the guiding catheter into the patient""s coronary artery over a guidewire until the balloon on the catheter is disposed within the stenotic region of the patient""s artery.
The balloon is inflated to open up the arterial passageway and increase the blood flow through the artery. Generally, the inflated diameter of the balloon is approximately the same diameter as the native diameter of the body lumen being dilated so as to complete the dilation but not over expand the artery wall. After the balloon is finally deflated, blood flow resumes through the dilated artery and the dilatation catheter can be removed therefrom.
In a large number of angioplasty procedures, there may be a restenosis, i.e. reformation of the arterial plaque in the dilated arterial region. To reduce the restenosis rate and to strengthen the dilated area, physicians now frequently implant an intravascular prosthesis called a stent inside the artery at the site of the lesion. Stents may also be used to repair vessels having an intimal flap or dissection or to generally strengthen a weakened section of a vessel. Stents are usually delivered to a desired location within a coronary artery in a contracted condition on a balloon of a catheter which is similar in many respects to a balloon angioplasty catheter, and expanded to a larger diameter by expansion of the balloon. The balloon is deflated to remove the catheter and the expanded stent is left in place within the artery. Stents with at least one end being nonperpendicular to the longitudinal axis, or angulated stents, have been proposed for use at the opening to an ostial branch of a main body lumen. Use of an angulated stent allows the expanded stent to match the arterial geometry, so that the entire stenosed region can be covered without the stent projecting into the main artery.
However, proper delivery and placement of an angulated stent is difficult, because the stent must be properly orientated to match the branch opening in the main artery wall, which may require rotation of the contracted stent mounted on the balloon before the stent is expanded. With conventional stent delivery systems, the distal section of the catheter within the body lumen is rotated by torquing the proximal section of the catheter which extends out of the patient. However, the torque applied to the proximal end of the catheter is not always transmitted to the distal end of the catheter due to frictional engagement within the guiding catheter and within the patient""s artery wall distal to the guiding catheter, and the mechanical loss from the tortuosity of the vessel. This causes an energy build up in the catheter, and any torque that is transmitted yields unpredictable results, leading to a lack of control over the catheter. The catheter may twist along its shaft, and a sudden release of the frictional engagement can cause the catheter shaft to untwist and the distal end xe2x80x9cwhipxe2x80x9d within the lumen. In other instances, the catheter does not untwist at all, and it may become so twisted that damage may occur to the catheter shaft. Therefore, the control needed to correctly orient an angulated stent does not exist.
Therefore, it would be a significant advance to provide a catheter with improved control over the orientation of the catheter distal end.
The present invention is directed to an intraluminal catheter having a catheter shaft and a distal member rotatable-relative to at least a section of the catheter shaft. In one embodiment, the catheter has-a catheter shaft, a distal member, which in a presently preferred embodiment is a balloon mounted on a distal portion of the shaft, and a tubular sealing member having an expandable portion disposed at least in part within a section of the distal member. The tubular sealing member has an expanded configuration, and an unexpanded configuration expandable into contact with the section of the distal member, so that the distal member is rotatable relative to at least a section of the catheter shaft and to the tubular sealing member when the tubular sealing member is in the unexpanded configuration. While discussed herein primarily in terms of a rotatable distal balloon, it should be understood that the distal member may be other operative members commonly provided on a catheter distal shaft section.
In one embodiment, the catheter shaft includes an outer tubular member defining an inflation lumen and having the tubular sealing member secured to a distal end of the outer tubular member, and an inner rotatable member rotatably disposed within the outer tubular member lumen when the tubular sealing member is in the unexpanded configuration. The inner rotatable member preferably extends distally out the distal end of the outer tubular member. In one embodiment, the balloon is disposed about and secured to a distal portion of the inner rotatable member, and the tubular sealing member radially expands into contact with a section of the balloon when pressure is introduced into the outer tubular member and tubular sealing member lumens. In a preferred embodiment, the balloon distal shaft is secured to the inner rotatable member prior to insertion into the patient""s body lumen, however, the balloon distal shaft may be secured at any time after insertion as well. With the tubular sealing member in the unexpanded configuration, the balloon on the distal end of the catheter within a patient""s body lumen can be rotated by torquing a proximal section of the inner rotatable member which extends outside of the patient. As a result, the inner rotatable member rotates relative to the outer tubular member, causing the balloon secured thereto to rotate. In a presently preferred embodiment, the tubular sealing member is disposed at least in part within a proximal shaft of the balloon. When inflation fluid is introduced into the inflation lumen, the tubular sealing member expands against the balloon proximal shaft, thus providing integrity between the inflation lumen and the balloon interior, allowing the balloon to be inflated. The tubular sealing member expands upon contact with the inflation fluid, preferably at a rate faster than the rate of balloon expansion, until it contacts the balloon shaft. At contact, the tubular sealing member secures, preferably releasably, to the balloon shaft, and seals the inflation lumen, effectively securing the rotatable balloon in a locked position for inflation. Thus, with the tubular sealing member in the expanded configuration, the balloon is typically not rotatable relative to the tubular sealing member. In one embodiment, a fluid tight seal is formed between the expanded tubular sealing member and the balloon proximal shaft.
In one embodiment, the catheter has an inflation lumen, a proximal shaft section, a distal shaft section having at least a portion which is-rotatable about the longitudinal axis of the catheter independent of the proximal shaft section, and a tubular sealing member having an expandable portion having an expanded configuration and an unexpanded configuration disposed within the distal shaft section of the catheter which radially expands into contact with the distal shaft section when inflation fluid is introduced into the inflation lumen.
In one embodiment, the catheter of the invention allows for a degree of translational (i.e., longitiudinal) movement in the rotatable member relative nonrotating shaft sections. Thus, in one embodiment, the inner rotatable member can be moved longitudinally relative to the outer tubular member, preferably when the tubular sealing member is in the unexpanded configuration.
The catheter of the invention may be configured for a variety of therapeutic or diagnostic uses such as balloon angioplasty, stent delivery, and drug delivery. In one embodiment, the catheter includes an angulated stent having a truncated end mounted on the balloon for delivery and deployment within a branch vessel of a patient""s body lumen. In another embodiment, a drug delivery device may be placed on the distal end of a catheter. For example, a drug may be located on a stent carried by a balloon. The drug may be placed on only a portion of the delivery device and delivered to a specific area within the lumen. The delivery device may need rotation to properly align the drug delivery with the required location. Additionally, catheters without balloons may also be used in localized drug delivery.